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Table 2 Intra- and inter-operator variation analysis for manual ICV estimation

From: A practical guideline for intracranial volume estimation in patients with Alzheimer's disease

  Op1 (Phase I) Op2 (Phase I) Op1 (Phase II) Δ o p 1 1 Δ o p 1 2 MRPA 1 MRPA 1
AD 1.4870 ± 0.16418* 1.4870 ± 0.16416 1.4870 ± 0.16418 p = 0.55 p = 0.23 0.002 0.004
AC 1.4609 ± 0.14444 1.4610 ± 0.14436 1.4609 ± 0.14446 p = 0.35 p = 0.33 0.002 0.014
  1. *ICV (mm3) presented as mean ± standard deviation (a factor of 106 has been taken from all values). Op1 (Phase I): ICV measurements performed by Op1 in phase I of the study; Op2 (Phase I): ICV measurements performed by Op2 in phase I of the study; Op1 (Phase II): ICV measurements performed by Op1 in phase II of the study; Δ o p 1 1 is the result for testing the null hypothesis that the ICV measurements performed by Op1 (Phase I) is not significantly different from ICV measurements performed by Op1 (Phase II). Δ o p 1 2 is the result for testing the null hypothesis that ICV measurement calculated manually by Op1 (Phase I) is not significantly different from ICV measurements done by Op2 (Phase II). Paired t-test is used. MRPAD1: Mean related percentage of absolute difference between ICV measurements performed by Op1 in Phase I and Phase II which provides intra-operator error in manual ICV estimation. MRPAD2: Mean related percentage of absolute difference between ICV measurements performed by Op1 and Op2 in Phase I which is related to inter-operator error; AD: Adult With Alzheimer's Disease subject group; AC: Adult Control subject group.